Utilizing renewable energy sources, such as winds and ocean waves, for creating electric power is becoming a more and more preferred energy producing system because it does not evaporate CO2 into the atmosphere.
Most energy producing plants today utilizes only one renewable energy source, mainly wind. These energy producing plants comprise several wind power units placed as separate units on land or in the ocean. When placed in the ocean the units normally are moulded to the ocean bottom with concrete pillars. This requires relatively shallow water and is therefore a placement used close to shore, thus normally close to habited or recreational areas. This placement is not desirable from an environmental view.
To build wind power plants further out to sea meets the problem of a usual greater depth, but also the practical economical problem of supervision and maintenance. Due to the fact that wind power plants up to today uses separate wind generator units, a placement further out to sea quickly becomes uneconomical.
The principle of placing an energy producing plants out on the ocean has the advantage that it there is normally a more frequent and harder wind. An energy producing plant placed out on the ocean can also be used as a platform for other types of energy converting systems, such as for example wave and sun energy converters.
However, an energy producing plant placed out on the ocean is exposed to hard wind and harsh weather. Thus, it is necessary that all components of the plant are durable and that the construction itself is rigid. It must also be easy to supervise and maintain.
In the applicant's previous application WO2011071444A1 such an energy producing plant is described. This plant is a floating platform comprising a frame work constructed of hollow pipes/beams connected by nodes. On each node a wind generator is placed. Each pipe/beam is sealed in its respective end and forms separate floating parts adapted to be connected to the nodes. Further, the volumes within each floating part, i.e. beams and nodes, are connected to each other. I.e. nodes and pipes/beams are connected so that the pipes/beams form transport paths between the nodes. The space in these parts can be used as transport paths, workshops, storage rooms, accommodations or provide space for other functions.
When the floating platform is exposed to the power of nature, all components are exposed to large forces which may result in large stress on the components, especially in the connection between the beams and nodes. Therefore all components must be correctly dimensioned. Thus, the size and price of the components and the entire platform increases.
In DE10219062A1 another floating platform comprising separate floating parts connected to each other in separate attachment points. The floating parts are able to articulate in relation to each other around a vertical axis arranged through the attachment points. However, the vertical forces from the waves are still risking damaging this attachment.
Another floating structure is disclosed in JP2007160965A. Here several separate floating structures are connected with tensioning parts in order to maintain a certain distance between each floating structure and to decrease manufacturing cost by replacing the ridged beams between each platform with the tensioning parts. However, these tensioning parts are not possible to adjust in any way.